This section provides background information related to the present disclosure which is not necessarily prior art.
Internal combustion engines are used in a wide variety of applications to provide a motive force to large and small-duty vehicles alike. The motive force applied to the particular vehicle is achieved by the combustion of a fuel with an oxidizer in a combustion chamber of the engine. The combustion of the fuel/oxidizer mixture within the combustion chamber causes the temperature and pressure within the combustion chamber to be elevated, thereby driving an element of the engine (i.e., a piston and crankshaft of an automobile) to propel the vehicle forward.
While combustion of the fuel/oxidizer within the combustion chamber provides adequate power to drive a vehicle, the combustion process results in an exhaust gas, which is typically discharged into the atmosphere via an exhaust pipe of the vehicle. Such exhaust gas typically includes particulate matter, which is formed when the exhaust from the engine mixes with ambient air. Specifically, when the exhaust gas mixes with ambient air, the combustion products present in the exhaust gas (i.e., soot, hydrocarbons, sulfates, nitrates, and ash) form via the physio-chemical processes of adsorption, condensation, and agglomeration into particles of various sizes.
The emission of particulates from exhaust gases of internal combustion engines such as diesel engines and gasoline direct-injection engines are restricted by various regulatory bodies both in the United States and abroad. The regulatory bodies responsible for controlling emissions from internal combustion engines promulgate various measurement methodologies and criteria to test exhaust gas and the resultant particulate matter therein. One such measurement methodology includes mixing and diluting a sample of exhaust gas with ambient air under controlled conditions. The flow of exhaust gas and air is passed through a particulate filter, which is subsequently analyzed to determine the weight of the particulate matter collected by the filter.
While collecting particulate matter on a filter from an exhaust gas/air mixture provides an accurate methodology for determining the amount of particulate matter contained within the exhaust gas, the integrity of such measurements is often compromised if the filters do not properly correspond to a particular test flow. For example, an emissions measurement test apparatus may include three phases, as required by Federal Test Procedure 75 (FTP-75), and, as a result, may likewise include three fluid test streams respectively associated with three filter media. Properly assigning each filter media to the particular phase prior to, during, and after the emissions test is essential to ensure the gravimetric data of each filter media is properly attributed to the particular phase.
If the filter media are not properly assigned to the various phases of the emissions test, the resulting data and, thus, the reported emissions for the engine, may be inaccurate. Inaccurate test results may result in the engine failing the particular standard and, thus, failing to meet certification. Accordingly, care must be taken when performing an emissions test to ensure that each filter media inserted into and removed from an emissions test apparatus is properly assigned to a particular phase of an emissions test prior to and following performance of the test to ensure accurate and reliable results.